Sound energy is produced when the propellant in a cartridge is ignited to force the bullet down the muzzle of a firearm. Suppressors (also known as silencers) for firearms operate by converting the majority of this sound energy to heat energy by diverting or trapping the pressurized gas in chambers within the suppressor body. The pressurised gas is forced to expand into the spaces within the suppressor, thereby decreasing the pressure, velocity and temperature of the gases prior to their release into the atmosphere.
A major advantage of using a sound suppressor is hearing protection for the firearm user and bystanders. In addition, the use of a sound suppressor helps to conceal the location of a firearm, which may be useful in military, police, sporting, hunting, and/or shooting situations. The delayed-release of the propellant gases may also reduce the recoil of the firearm and even increase the precision of a rifle.
U.S. Pat. No. 1,482,805 (Maxim), U.S. Pat. No. 3,748,956 (Hubner), U.S. Pat. No. 4,907,488 (Seberger), and U.S. Pat. No. 6,575,074 (Gaddini), and German Patent Number 19824730 (Joniskeit) provide examples of sound suppressors having a plurality of baffles with aligned openings for the passage of a bullet and propellant gases.
In Maxim, the baffles comprise a cylindrical rim of similar diameter to the outer body, wherein the edges opposite the bullet passageway are inclined to the axis of the outer body, thereby slowing the gases by directing them to adjacent baffles at an angle to the passage for the bullet.
In Hubner, the edges of the baffles comprise notches or serrations which are bent towards the muzzle of the firearm in order to disrupt the flow of gases. Hubner also discloses a return flow chamber adjacent to the entrance opening.
Seberger discloses a suppressor having a series of semispherical baffles with a plurality of holes in the circumference, wherein the holes in each adjacent baffle are aligned. In Seberger, each baffle is separated by a hollow cylindrical spacer wherein the diameter of the spacers is equal to that of the baffles.
Gaddini discloses a sound suppressor having a front end cap, at least one baffle element, and a rear end cap. The baffle element has an entrance aperture and an exit aperture. A spacer element, having at least one gas port and at least one notch, is positioned between the rear end cap and the baffle element. Expansion chambers are formed between the baffle element, the coaxial spacer and the front end cap. Once the firearm is discharged, the projectile gases pass through the rear end cap and flow forward and expand into the expansion chambers. The gases flow through the aperture of the baffle element and vent through the gas port in the spacer element, thereby creating an additional gas path. After moving through the gas paths in the suppressor, the gases are released via an aperture in the front end cap.
In Joniskeit, gases pass into expansion chambers and through a series of cross walls. The cross walls have gas holes which are offset from each other, thereby forming a tortuous path for the gases. After moving through the tortuous gas path in the suppressor (silencer), the gases are released via a gas outlet at the front of the suppressor.